/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.ha;

import org.apache.catalina.tribes.ChannelListener;
import org.apache.catalina.tribes.Member;

import java.io.Serializable;

/**
 * Receive SessionID cluster change from other backup node after primary session
 * node is failed.
 *
 * @author Peter Rossbach
 * @author Filip Hanik
 */
public abstract class ClusterListener implements ChannelListener {

	private static final org.apache.juli.logging.Log log =
			org.apache.juli.logging.LogFactory.getLog(ClusterListener.class);

	//--Instance Variables--------------------------------------

	/**
	 * The string manager for this package.
	 */

	protected CatalinaCluster cluster = null;

	//--Constructor---------------------------------------------

	public ClusterListener() {
		// NO-OP
	}

	//--Instance Getters/Setters--------------------------------

	public CatalinaCluster getCluster() {
		return cluster;
	}

	public void setCluster(CatalinaCluster cluster) {
		if (log.isDebugEnabled()) {
			if (cluster != null)
				log.debug("add ClusterListener " + this.toString() +
						" to cluster" + cluster);
			else
				log.debug("remove ClusterListener " + this.toString() +
						" from cluster");
		}
		this.cluster = cluster;
	}

	@Override
	public boolean equals(Object listener) {
		return super.equals(listener);
	}

	@Override
	public int hashCode() {
		return super.hashCode();
	}

	//--Logic---------------------------------------------------

	@Override
	public final void messageReceived(Serializable msg, Member member) {
		if (msg instanceof ClusterMessage) messageReceived((ClusterMessage) msg);
	}

	@Override
	public final boolean accept(Serializable msg, Member member) {
		if (msg instanceof ClusterMessage) return true;
		return false;
	}

	/**
	 * Callback from the cluster, when a message is received, The cluster will
	 * broadcast it invoking the messageReceived on the receiver.
	 *
	 * @param msg ClusterMessage - the message received from the cluster
	 */
	public abstract void messageReceived(ClusterMessage msg);

	/**
	 * Accept only SessionIDMessages
	 *
	 * @param msg ClusterMessage
	 * @return boolean - returns true to indicate that messageReceived should be
	 * invoked. If false is returned, the messageReceived method will
	 * not be invoked.
	 */
	public abstract boolean accept(ClusterMessage msg);

}
